Fix typings for EditorComponentField (#7160)

* fix: make EditorComponentField type handle widget='list' correctly

* fix: make field and fields optional for widget='list'

---------

Co-authored-by: Anze Demsar <anze.demsar@p-m.si>

packages/decap-cms-core/index.d.ts

@@ -409,19 +409,24 @@ declare module 'decap-cms-core' {
     config: CmsConfig;
   }
 
-  export interface EditorComponentField {
-    name: string;
-    label: string;
-    widget: string;
-    /**
-     * Used if widget === "list" to create a flat array
-     */
-    field: EditorComponentField;
-    /**
-     * Used if widget === "list" to create an array of objects
-     */
-    fields: EditorComponentField[];
-  }
+  export type EditorComponentField =
+    | ({
+        name: string;
+        label: string;
+      } & {
+        widget: Omit<string, 'list'>;
+      })
+    | {
+        widget: 'list';
+        /**
+         * Used if widget === "list" to create a flat array
+         */
+        field?: EditorComponentField;
+        /**
+         * Used if widget === "list" to create an array of objects
+         */
+        fields?: EditorComponentField[];
+      };
 
   export interface EditorComponentOptions {
     id: string;